1. Field of the Invention.
This invention relates to new and improved apparatus and method for the virtually immediate and substantially complete separation of immiscible liquids; which are particularly adapted to such separation of sample liquids from immiscible isolation liquids within which the sample liquids are encapsulated for minimization of sample liquid carryover attendant automated sample liquid analysis.
2. Description of the Prior Art.
Although a number of apparatus and methods are known for the substantial separation of sample liquids from immiscible isolation liquids within which the same are encapsulated for minimization of sample liquid carryover attendant sample liquid analysis, these will generally be found to rely primarily upon the natural separational effects of the differences in specific gravity between those liquids, and are thus not effective to accomplish the virtually immediate, and complete in terms of totally different locations of the thusly substantially separated liquids, separation of the liquids as are inherently provided by the apparatus and method of this invention.
More specifically, U.S. Pat. No. 4,121,466 issued Oct. 24, 1978 to Allen Reickler, et al, for "Liquid Dispenser With An Improved Probe" and assigned to the assignee her discloses the use of an immiscible hydrophobic isolation liquid to encapsulate successive aqueous sample liquids for minimization of sample liquid carryover attendant sample liquid analysis. In this apparatus, wherein the isolation liquid is of greater density than the sample liquids, the former is simply allowed to settle out from the latter to the bottom of a reaction receptacle into which the isolation liquid-encapsulated sample liquids are dispensed, thereby leaving the sample liquid readily accessible for reaction with reagent liquids as may then be introduced into the receptacle. This settling out of the isolation liquid can and does take time and, in any event, leaves the thusly separated isolation and sample liquids in essentially the same location, e.g. the reaction receptacle.
In like manner, U.S. Pat. No. 4,357,301 issued Nov. 2, 1982 to Michael M. Cassaday, et al for "Reaction Cuvette" and assigned to the assignee hereof, also discloses the use of an immiscible isolation liquid to encapsulate successive aqueous sample liquids for minimization of sample liquid carryover attendant sample liquid analysis. In this apparatus wherein the isolation liquid is again hydrophobic and apparently of greater density than the sample liquids, sharp projections or the like of a hydrophilic material are provided at the bottom of the reaction cuvette, and operate to puncture the isolation liquid-encapsulated sample liquids as the same are introduced into the cuvette; thereby freeing for reaction the sample liquids from the isolation liquid which essentially sinks to the bottom of the cuvette. Again, this separation can and does take time and, in any event, leaves the isolation liquid and sample liquids in the location, e.g. the reaction cuvette and, of course, in substantial surface contact at the isolation liquid-sample liquid interface.
Under the above circumstances, it has been determined by applicants that the continued presence of the "separated" isolation liquid with the sample liquid at essentially the same location, and with substantial surface contact therebetween at the isolation liquid-sample liquid interface, can and does present significant problems with regard to the accuracy of subsequent sample liquid analysis results; and especially in those instances wherein those sample liquid analysis results are arrived at through use of sample liquid analysis methodologies involving, for example, reflectance spectroscopy or ion selective electrodes, colorimetry, cell counting and/or enzyme coil operation.
Hydrophobic filtration, for example as disclosed by the "non-wet" filter of U.S. Pat. No. 4,266,559 issued May 12, 1981 to David S. Akhavi for "Blood Sampler," wherein a filter of hydrophobic material is used to prevent the escape of an aqueous sample liquid from a collection device while permitting the passage of air therethrough to enable filling of the device, is also known in the prior art; but is not seen as relevant to the separation of immiscible liquids as disclosed herein.
Also of limited relevance to immiscible liquid separation are conventional debubbler devices which have now become standard in continuous flow sample liquid analysis systems and which operate to remove the air segments from a continuously flowing, air segmented sample liquid stream prior to sample liquid analysis. These debubbler devices, which operate primarily on the very significant differences in specific gravity between air and sample liquids are clearly totally irrelevant to the separation of immiscible liquids as disclosed herein.
No relevant prior art is, in any event, known to applicants with regard to the combination of immiscible sample and isolation liquid separational and sample liquid reaction devices to effectively combine those functions in the manner made possible by the apparatus and method of this invention.